watch maker question 1

[MRSSPOCK]

I realise I am probably not posting this question in the proper area, and probably not even on the proper forum, but here goes anyway.
Does anybody have any idea what is the function of the part I have marked with a red "X" in the image below.
The shaft which it passes has a scallop machined out to provide clearance for this pointed piece, but what on earth is that piece doing?
I can't see that it interacts with any other moving part.

 

[LittleInch]

Perhaps it makes the tick tock noise?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[zeusfaber]

Por yourself a drink that will last you a while, then try Googling "balance wheel escapement guard pin" or "balance wheel escapement guard dart"

It helps keep things in the right place when somebody drops their watch.

A.

 

[MRSSPOCK]

That's great. Thanks zeusfaber. Now it makes sense.

I didn't need the drink, but probably will soon. The impulse roller jewel has gone.

This is my first time working at a watch. I took the rear cover off to see if I could see anything amiss. It took me a while to realise that jewel was missing.

So maybe it is inside the gearbox, or could have fallen out when I opened the door.

How on earth do they create that aperture which the impulse jewel fits into, since it is a partial circle with a flat on it. The whole thing amazes me.

I guess it is just a tight fit that keeps the jewel in there? (or not in there in this case! )

EDIT: I just discovered they are held in with shellac, or superglue.

 

[dik]

I was in Grade 7 when I first disassembled a watch... it was a Gruen mechanical... I reassembled it, except I had to get a jeweller to put the last plate in place. It had 3 jewels in that plate, and I could only get 2 of the three pins aligned.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik